1. Field of the Invention
The present invention relates to lithographic plates, such as presensitized (PS) plates, laser beam printer (LBP) plates, and pink plates.
2. Description of the Related Art
Examples of lithographic plates currently used in the field of light printing include direct drawing type printing plates such as LBP plates, electrophotographic plates such as pink plates, PS plates, and the like. An LBP plate is composed essentially of a substrate and a hydrophilic layer formed on the substrate, the hydrophilic layer functioning as an image receiving layer. A pink plate is composed essentially of an electrically conductive substrate and a photoconductive layer formed on the substrate, the photoconductive layer functioning as an image receiving layer. A PS plate is composed essentially of a substrate and a sensitized layer, e.g., a diazo sensitized layer, that is formed on the substrate, the sensitized layer functioning as an image receiving layer.
Examples of known materials for lithographic plates are aluminum plates, paper, plastic films, etc., as disclosed in Japanese Laid-Open Patent Publication Nos. 58-94497, 62-77936, and 4-320844. However, aluminum plates are expensive as well as difficult to handle. Paper is inexpensive but has poor durability and poor water resistance. Plastic films, which are known to overcome the above-mentioned problems, have insufficient flexibility and insufficient film strength after being bent, thus resulting in the problems of poor durability and insufficient printability when being wound around a print drum.